The present invention relates to a process for separating iron, zinc and lead from flue dust and/or flue sludge by filtration.
Flue gases, particularly from blast furnaces carry a considerable quantity of flue dust, i.e., large and small particles of fine ore, coke dust and the like. In order to permit its further use as a fuel gas in furnaces, hearths and machines, cleaning is necessary which involves the use of conventional dust removal and/or gas cleaning methods, for example using scrubbers, centrifugal separators, as well as mechanical and electrostatic precipitators. Most of the flue gas and/or sludge obtained through cleaning the gas is again fed to the blast furnace after prior sintering.
In addition to iron and carbon, the flue dust and/or sludge also contains heavy metals, particularly lead and zinc which have hitherto been fed to the blast furnace again with the remaining flue dust. However, for various reasons their removal is desired.